Skip to main content

MongoDB: Getting Started With CRUD Operations

Image
By


MongoDB is a No-SQL open source database system that stores information in documents.

MongoDB was created with excellent performance and accessibility in mind.

A document is a collection of fields and value pair combinations that are stored in BSON (binary representation of JSON records), which is the native data type in most languages.

MongoDB uses collections to hold groups of documents.



Now let’s see the basic operations that can be handled in MongoDB.
  •          Create
  •          Read
  •          Update
  •         Delete

collectively called the "CRUD operation"


Create Operation

MongoDB performs atomic creation operations on single documents. It adds a new document to the selected collection.

db.{collection_name}.insert({
                 field => value,
                 field => value,
                 field => value,
});

The value could be a simple datatype or something more complex (document or array).

The Create operation always adds the unique identifier of the ObjectId data type to the newly created document.

ObjectId is a 12-byte BSON primarily used to maintain uniqueness in a collection.

The following is the byte structure of ObjectId.


  • 4 byte for Unix epoch value
  • 3 byte for machine identifier
  • 2 byte for process identifier
  • 3 byte for some random value

Example

db.user.insert({
                name : 'Zainul',
                email: 'zainabed@gmail.com',
                address : 'XYZ Address'
})

Read Operation

The Read operation fetches documents from a single or selected collection. It uses projection and conditions to modify the resulting documents.

  • Project is used to retrieve only specific fields of a document, which speeds up the read operation.
  • Condition is used to select a particular document which falls under a given condition.


db.{collection}.find(
           { condition },
           { projection }
)

We can use limit and sort to limit and order the resulting documents.

Note: the order of resulting documents is not defined unless we provide an order for documents.


Example 
db.user.find(
        { name: 'Zainul' }, { name : 1, email : 1}
)

This command will return a set of documents from a user collection whose name matches the given condition, and will fetch only the name and email.

Note: the read operation always returns an ID unless we omit it by using query projection.


Update Operation

Update operations modify existing documents or even create new documents. It uses update criteria to isolate documents and update actions to modify the values of selected documents.

db.{collection}.update(
           { update criteria },
           { update action },
           { update option }
)

The Update option tells MongoDB to update multiple documents.

example

db.user.update(
        { name : 'Zainul' },
        { $set : { name :  'Abedin' } }
)

Note: Use upsert to create a new document if that document does not exist.



Delete Operation

The Delete operation removes single or multiple documents from a selected collection. It uses remove criteria to identify the document that is to be removed.


db.{collection}.remove(
     {remove criteria}
)

If the criteria for removal are not defined, then it will remove all the documents.

example

db.use.remove(
      { name :  'Abedin' }
)

Conclusion 

In this post, you learned about MongoDB's architecture, learned about CRUD operations in MongoDB, and saw some examples of how to use CRUD operations in MongoDB. Hopefully, you now have a clear understanding on how to apply these principles to your MongoDB project.
Labels:

Comments

Post a Comment

Subscribe for latest tutorial updates

* indicates required

Popular posts from this blog

AJAX - How To Retrieve JSON Response from PHP script

By
Hello Friends, This is my first tutorial post. Today I'll explain you how to retrieve JSON response via Ajax call. First we build a PHP script to send response in JSON format, then we will gather this response from an Ajax call through jQuery script. Let’s first create a PHP script  Create a PHP script, I’ll name it as “json_response.php” And add following code in it json_response.php <?php //set header for JSON response header("Content-Type: application/json"); //render array in JSON format echo json_encode(array('status' => 200, 'message' => 'Response from PHP script in JSON format.')); This is a basic example to send JSON response. PHP script will send response with status code and message. Now create a HTML file to fetch JSON response and add it in header tag. Create a HTML file, I’ll name it as “json_response.html” And add following code. json_response.html <html>           ...
Post a Comment
Read more

JSON Tutorials : Getting Started

By
JSON is widely accepted text formatted structured data. JSON stands for " JavaScript Object Notation ". In general JSON can represent 1. Object of database record. 2. Object to represent a list of HTML elements. 3. Result of search query. 4. Response of an Ajax call. Here you can see JSON is used in many different areas and for many different scenarios. This means it has simple data structure. most of programming languages adopt it and it can flow easily from one connection to another. You can find JSON office definition here JSON Official Site . JSON is represented by two structural types, which includes two primitive types. Structural types Array : A sequential list of primitive data types between square brackets [ ] Object : Collection of key, value pair stored inside curly braces { }, where value would be primitive data type Primitive types : There are two primitive types key and value. " key " should be string and " value (data type)...
Post a Comment
Read more

Twig Tutorials: Install and Configure

By
In this tutorial, we'll look at how to install Twig within your PHP project and thereafter configure it so that we can create and use a Twig template inside our PHP web application. Later on, we'll see a simple Twig template example that displays a "Welcome to Twig template" message. Let's take it one step at a time. Install The Twig template can be installed using Composer, Git, or PEAR. In this tutorial, we will use Composer to install Twig. To do so, we'll need to make a "composer.json" file. { "require" : { "twig/twig" : "1.*" } } From the console, run the following command . $ php composer.phar install This command will install Twig library. Configuration To use the Twig template, we should first configure it. To achieve this, we will write an index.php file which will configure the Twig autoloader and generate the Twig environment. We will render the Twig temp...
Post a Comment
Read more